Definitely withings. I have had a steel HR for 2,5 years now and I still love it. You can buy any standard wristband that you like and the battery lasts a month. It’s also waterproof so no worries there. Plus I like the more traditional look, so it still looks good when wearing a bit more formal clothes.
That’s what we call them in German. Milchzähne. I’m guessing because they develop while you’re still drinking your mother’s milk?